FIMP and Muon ($g-2$) in a U$(1)_{L_{\mu}-L_{\tau}}$ Model

Understand

The tightening of the constraints on the standard thermal WIMP scenario has forced physicists to propose alternative dark matter (DM) models.

• One of the most popular alternate explanations of the origin of DM is the non-thermal production of DM via freeze-in.
• In this scenario the DM never attains thermal equilibrium with the thermal soup because of its feeble coupling strength ($\sim 10^{-12}$) with the other particles in the thermal bath and is generally called the Feebly Interacting Massive Particle (FIMP).
• In this work, we present a gauged U(1)$_{L_{\mu}-L_{\tau}}$ extension of the Standard Model (SM) which has a scalar FIMP DM candidate and can consistently explain the DM relic density bound.